This proposal builds on our established findings and methods and extends them in 4 new directions: 1. We hypothesize that formal training will cause measurable anatomical and biochemical changes in brain, when comparison is made with appropriate control conditions. Effects of experiments with formal training will be compared with results already obtained from differential informal experience. 2. We hypothesize that recovery of function after brain damage can be promoted by a combination of enriched environment and stimulating drugs or imparied by impoverished environment and depressant drugs. Research on reorganization of function has both theoretical and applied values. Such animal research may provide a basis for applied research directed toward improved treatment of human patients. 3. We hypothesize that the cerebral and behavioral effects of enriched and impoverished experience already obtained in several species of rodents will be found in other orders of mammals. Since investigators are extrapolating the results to brain mechanisms of learning and memory of mammals in general, it is important to test directly whether similar effects will occur in a different order of mammal. The research designs that have been successful with rodents can be applied directly and relatively economically to cats. 4. Study effects of drugs on brain biochemistry and memory in mice, emphasizing two hypotheses: (a) RNA does not have to be synthesized immediately after learning in order for long-term memory of this training to be formed. This will be tested by determining the minimum time that synthesis of protein must proceed after training. (b) Establishment of long-term memory requires simultaneous arousal and ability to synthesize protein. This will be tested by modifying arousal during periods in which protein synthesis is permitted or is blocked by inhibitors.